1 files changed, 11 insertions, 3 deletions
diff --git a/mdk-stage1/dietlibc/lib/vfprintf.c b/mdk-stage1/dietlibc/lib/vfprintf.c
index 03dfe87a9..c33a2404b 100644
--- a/mdk-stage1/dietlibc/lib/vfprintf.c
+++ b/mdk-stage1/dietlibc/lib/vfprintf.c
@@ -1,11 +1,19 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include "dietstdarg.h"
 
 int vfprintf(FILE *fstream, const char *format, va_list ap)
 {
-  char tmp[1000000];
-  size_t n = vsnprintf(tmp, sizeof(tmp), format, ap);
-  fwrite(tmp, n, 1, fstream);
+  char *tmp;
+  va_list cp_ap;
+  size_t n = 0;
+
+  va_copy(cp_ap, ap);
+  n=vsnprintf(0, 1000000, format, cp_ap);
+  tmp=alloca(n+2);
+  vsnprintf(tmp, n+1, format, ap);
+  fwrite(tmp, n,1, fstream);
   return n;
 }
+